Al Jazeera said in a blog post on its English website that it had been contacted by friends of Ghonim and that he has been missing "since last week. His wife is appealing for any information on his whereabouts. Ghonim was guest speaker at the Al Jazeera Forum for Online Journalism & Freedom of Opinion earlier this month."

On what appears to be Ghonim's Facebook page, it says he admires Egyptian opposition figure Mohamed ElBaradei, who recently returned to Egypt to take part in the nationwide protests against the government of President Hosni Mubarak, who has been in power for more than 30 years.

Gohnim's page also lists Bill Gates, Warren Buffett and Steve Jobs as people who inspire him.

According to Ghonim's LinkedIn page, he graduated from the American University in Cairo in 2007 with an MBA after getting a bachelor's degree from Cairo University in 2004. The page says he has been Google's marketing head since January 2010. It also lists him as being based in the United Arab Emirates.

On his Twitter account, @Gohnim, he posted messages that indicate active participation in protests in Egypt.

Google declined to confirm if Ghonim was in fact missing. A spokeswoman did say in an e-mail: "We care deeply about the safety of our employees, but to protect their privacy, we don't comment on the individually."